Thermostatic control



June 8, 1954 F. H. MUMBERG THERMOSTATIC CONTROL 2 Sheets-Sheet l FiledDec. 21, 1950 l I N V IEN TOR. f77/Z flying/Mfg BY June 8, 1954 F. H.MUMBERG 2,680,792

THERMosTATIc CONTROL Filed Deo. 2l, 1950 2 Sheets-Sheet 2 lj I fINVENTOR ATTORNEYS Patented June 8, 1.954

UNITE STATS PATENT QFFICE THERMOSTATIC CONTROL Fritz Henry Mumberg,Philadelphia, Pa.

Appiication December 21, 1950, Serial No. 202,073

4 Claims. l

This invention relates to a thermal regulation device and moreparticularly to a thermal control in which mercury is the thermalsensitive substance and an adjustable contact is provided forv makingelectrical contact with the mercury.

It is an object of this invention to provide a thermal sensitive deviceemploying a column of mercury which can be easily increased anddecreased in volume.

It is another object of this invention to provide a thermal sensitivedevice having an adjustable electrical contact completed between amercury column and an adjustable wire contact both of which are sealedin a tube.

It is a still further object of this invention to provide a thermalsensitive device in which an adjustable contact sealed in a tubecompletes an electrical circuit by contacting a mercury column and whichis electrically attached to a wire outn side of the sealed tube by meanswhich do not hinder the adjustment of said adjustable contact.

These and other objects of this invention will become more apparent uponconsideration of the following description taken together with theaccompanying drawings in which:

sig. l is a front sectional View ci the thermal control of thisinvention;

Fig. 2 is a front sectional View oi the upper end of the thermal controloi Fig. l;

Fig. 3 is an enlarged sectional view of a portion of the thermal controlof Fig. l;

Fig. 4 is a radial section of the thermal control of this inventiontaken on lines iwi of Fig. 2 in the direction of the arrows;

Fig. 5 is a front sectional View of another thermal control of thisinvention;

Fig. 6 is a front sectional view of a central section of the thermalcontrol shown in Fig. 5;

Fig. 7 is a radial section of the thermal control of Fig. 6 taken online 1--7 in the direction of the arrows; and

Fig. 8 is a radial section of the thermal control of Fig. 6 taken online il-S in the direction of the arrows.

This application is a continuation in part of my copending application,Serial No. 142,207, filed February 3, 1950, now abandoned, torThermostatic Control.

A thermal control It is shown in Fig. l made up of an outer tube IIenveloping an inner tube I2 molded into its lower end into a thickenedstem I3. At the bottom of the thickened stem I3 a bulb-like mercuryreservoir i4 is provided from which a capillary tube I5 extends upwardthrough the thick walls of the stem I3 to thin walls I6 at the lower endof the outer envelope tube I I. A

short distance up the envelope tube II, the thin walls IS widen to formthe inner tube I2 which extends upward through the outer tube II to apointed seal-ofi" I'l adjacent the upper end of the thermal control Iii.

The inner tube I2 is divided into two compartments A and B by a centralradial wall I8. The compartment A is the lower compartment as shown inFig. 1 and contains walls IS which are extensions of the walls IS abovethe point where the lower end of the tube I2 branches oil from the wallsI5. The walls It extend upwardly forming the upper end of the capillarytube to a point where, spreading out, a cup 2t is formed. The cup 20 hasa flared-out upper lip 2| which abuts the inner surface of thecompartment A throughout its circumference. The upper compartment Bcontains a sleeve 22 as shown best in Fig. 2. The sleeve 22 is supportedat the upper end of compartment B. Referring to Fig. 4, it is seen thatthe sleeve 22 is centered in the compartment B of the tube I 2l by aninsulating separator 23 which is corrugated to space the sleeve 22 fromthe inner surface oi the compartment B and to hold it in position by afriction t. Supported inturn in the sleeve 22 is a metal threaded rod 24as shown in Figs. 1 and 2. The lower edge of the sleeve 22 is turnedinward to form a seat which grasps and supports a metal block 25. Theblock 25 is centrally threaded to receive and support the threaded rod24 which is thus centered and supportedin the compartment B of the innertube I2. At its lower end, the rod 2li is provided. with a slit whichreceives and holds a wire 20. The wire 23 extends downwardly from thethreaded rod 24 and through a suitable aperture in the central wall Itinto the lower compartment A. In the lower compartment A, the wire 2eextends into the cup 20 and into the upper end of the capillary tube I5.

A thermal control I it is shown in Fig. 5 made up of an outer tube IIIand an inner tube H2. At the lower end of the outer tube l l i there isa thickened stem I i3 which has at its end a mercury reservoir II4.Acapillary tube H5 extends axially upward through the thick walls ci thestern Il?, from the reservoir l Iii. At the upper end of the thickenedstern H3 a thin wall llt extends to the lower end of theinner tube I i2.The capillary tube I I5 extends upward axially through the tubular wallIIS. The thin wall llt widens to form the inner tube H2 which, in turn,extends upward through the outer tube lil to a point at seal-oli I Iladjacent the upper end of the thermal control H0.

The inner tube H2 is divided into two compartments U and L by a narrowwaist portion IIS. The compartment L is the lower compartment shown inFig. 5 and contains a wall ||9 which is a straight extension of the walllit above and within the lower end of the inner tube |22. The wall H9extends upwardly and at its upper end spreads out into a cup 12d. Thecapillary tube I5 extends axially within the wall ||9 to the cup |26.The cup |26 has a lip |2| which peripherally contacts the inner wall ofthe tube i l2 throughout its entire circumference. The waist ||3contains a bolt |22 which has an external thread |23 and receives athreaded rod |2il in an internal thread |25 bored axially through itscenter. The threaded rod |24 carries a contact wire |25 which extendsdownwardly from the threaded rod |24 through the lower compartment L andinto the cup |2|l and the upper end of the capillary tube H5. As shownin Fig. 6, the bolt |22 is held in place on the waist H2 by a head |45formed on the lower end of the bolt |22 and a nut |46 screwing on thethreads |23. The head |45 has a sloping wall Uil and the nut |45 bearsagainst a spring |48. The waist IIS forms a circular shoulder |49 at thebottom of the upper compartment U and a circular shoulder |52 at the topof the lower compartment L. The spring |43 seats on the shoulder |49 andis urged thereagainst by the nut |46. The sloping wall |4'i' seatsagainst the shoulder Het and is drawn thereagainst by the tighteningaction of the nut |46 on the threads |23. The spring |48 pressed betweenthe shoulder It@ and the nut |4E applies a seating force on the wall illagainst the bolt |59. This seating force between the smooth wall lilland the smooth shoulder l5@ can provide a mercury tight lit betweenthese parts. A body of mercury |5| is contained in the lower part of theupper compartment view around the bolt |22 and the spring |118 and nut|135.

The adjustment of the thermal control is obtained by magnetism betweenthe parts at the upper end of the thermal control. As seen in Fig. theupper end of the outer tube is covered by a cap 2l which ts snugly overthe top and down the outer surface of the walls of the tubes -for ashort distance. An annular field magnet 23 encircles the tubeimmediately below the cap 2l and is supported on the cap 2l by a threadcoupling 29. The eld magnet 28 creates a directional magnetic fieldhaving lines of force aligned radially across the tubes and i2 in thearea encompassed by the magnet 28. The threaded rod 24 is so positionedin the compartment B that its upper end lies within this magnetic eld.An armature to is formed on the upper end of the threaded rod 24. Thearmature Sil is formed of a magnetic responsive substance and shaped asto be under the influence of the magnetic field of the field magnet 28.The rod 24| is so threaded in the block 25 as to be readily rotatable inthe block 25. The coupling 29 is provided with an inwardly turned rim 3|which engages outwardly turned flange 32 on the lower end of the cap 2l.The t provided between the rim 3| and the flange 32 is sufficientlyloose to permit rotation oi the coupling 29 on the cap 2l. Consequently,the eld magnet 28 can be rotated around the outer tube I| and thedirection of the lines of force of its consequent magnetic field withinthe tubes and I2 can be correspondingly shifted. When the lines of forceare thus revolved, the armature 3d is correspondingly influenced and isrotated on the axis of the threaded rod. The threaded rod being screwedinto the block 25 will thread up or down through the block 25 dependingupon the direction of the rotation of the armature 3Q as brought aboutby the rotation of the eld magnet 2S as seen as looking downward fromabove in Fig. 4. When the armature 3B is rotated clockwise, the threadedrod screws downwardly through the block 25 while conversely, when thearmature 3d is rotated counter-clockwise, the threaded rod 2t screwsupwardly through the stationary block 25. Thus, in this manner, therotation of the eld magnet can be employed to alter and determine theaxial position or the threaded rod 24, and conseduently, the wire 26.

Similarly, the wire |2t can be moved up and down in the lowercompartment L of the thermal control lil shown in Figs. 5 and 6. Anarmature |36 is provided at the upper end of threaded rod |24. rThisarmature |30 may be subjected to the action of a eld magnet and rotatedin the same manner as the armature Sil referred to above in connectionwith Figs. l., 2 and 4. rThe iield magnet and cap structure is not shownin Figs. 5 and 6 but the cap 2l, field magnet 28 and coupling 29 ofFigs. l, 2 and 1l can be applied to the thermal control of Figs. 5 and 6and rotate the armature |32 with equal facility. Such a rotation of thearmature |351 causes the threaded rod |24 to rotate in the threadedbore. When the threaded rod |2d rotates in a counter-clockwise directionas seen in Fig. 7, the armature i3d, threaded rod 52d and wire |26assembly moves upward in the thermal control lill. Conversely, when thethreaded rod rotates clockwise as seen in Fig. '7, the assembly movesdownward in the control |0.

The electrical contact in the thermal control l i@ is achieved by makingand breaking contact between two wires |33 and 236| which enter thethermal control llt at the top. ri'he wire |34 extends into the outertube and downwardly between the outer tube i|| and the inner tube H2 onthe right side, as seen in the figures to a knob |36 formed on the thinwall |6 adjacent the lower end of the tube lil. The wire |24 is anchoredon the knob |35 as shown in Fig. 6. A short lead-in wire |3| is wrappedaround the wire immediately above the knob |36 and passing through theknob |35 is bent at right angles to penetrate the wall |6 and extendinto the capillary tube i5 and thus provide an electrical contactsurface |32 in the capillary tube at this point. The other wire |33extends down the lei t side o1" the tube ||2 a short distance to agirdle |3t of solder encircling the wai-st l |3. As shown in Fig. 8, thesolder girdle |39 anchors the end of the wire |33. A lead-in wire |1l|extends from the solder girdle |39 through the inner tube ||2 andprojects into and contacts the mercury |5| in the upper compartment U.

The mercury pool |5| surrounds and is in contact with the metallic bolt|22. The threaded rod |2=t in turn is in electrical contact with thebolt |22. Thus, the wire |26 is in electrical contact with the lead-inwire |33 through the solder girdle |39, the lead-in wire Mi, the mercurypool ii, the bolt |22 and the threaded rod |24.

in the thermal control of Figs. l to fi, mercury fills the reservoir Hdand capillary tube H5. The level of the mercury in the capillary tube |5can be adjusted while the thermal control lil is not in operation byheating the reservoir |94 to expand the column of mercury in the tube||5 up into the cup |26 where it will reach the level of a port |44 inone side of the cup |20. lThe mercury upon increased heat applied to thereservoir H4 will run out the port |44 and collect in the bottom of thecompartment L. The mercury thus overflowing can be stored in thecompartment L. When the reservoir H4 is subsequently cooled, the levelof the mercury in column i5 will recede from the cup 20 to anypredetermined point according to the temperature at which the thermalcontrol is to be operated.

The operation of the two thermal control devices in the aboveembodiments of this invention is essentially the same. The followingdescription of the operation of the invention is therefore hereinafterdescribed in connection with the embodiment shown in Figs. 5 to 8. Itwill be understood however that the operation oi the embodiment shown inFigs. l to 4 is essentially the same. In operation, this device is firstadjusted to a desired range of temperatures by predetermining the levelof the mercury column in the capillary tube l i5 by the above describedprocedure. A second adjustment is obtained by the axial movement of therod |24 as described in connection with the field magnet. With these twoadjustments, the thermal control lvcan be set to open and, close theContact between the wires |33 and i3d over a wide range of temperatures.The contact between the wires |33 and 35i is closed by the column ofmercury lirst contacting contact |38 and then rising to con tact wire|25.

The thermal control of this invention is susceptible of adjustment tosensitivity in heat changes over a wide variety of temperatures. At thesame time, the control I le is adjustable to be accurately actuated at apredetermined temperature by a change in temperature. The sensitivity ofthis thermal control is based upon the contact which is made or brokenbetween the wires |33 and i3d by the wire lii and the mercury column inthe capillary tube i l5. The contact is established from wire |33 towire |3l through the girdle element E39, the lead in wire |4|, themercury pool i5|, the threaded bolt |22, if

point of contact it is possible to vary the temi;

perature at which the electrical circuit is completed. Tais variation ofthe temperature at which the circuit will be completed is dependent uponboth the amount oi extension of the wire |'2t` into the capillary tubeSI5 and the height of the mercury column in the capillary tube l5 at anygiven temperature. Also, this variability provides the thermal controllill or" this invention with a wide range of temperatures at which itwill operate and with a high selective sensitivity in operatinfr at anytemperature in this wide range of temperatures.

The higher the column of mercury stands in thecapillary tube l l5 thelower the temperature at which the circuit will be completed for anygiven position of the wire |26. C'orrespondingly, the further the wire|26 is inserted in the capillary tube |5 the lower the temperature atwhich the circuit will be completed for any given amount of mercury inthe capillary tube H5. The temperature for closing the circuit can thusbe varied by increasing or decreasing the amount of mercury in thecapillary tube and thereby lower or raisethe level of the mercury columnat any given temperature. The temperature of the completion of thecircuit may also be varied by the axial movement of the wire in or outof the capillary tube H5. The wire |25 may be readily moved axially byrotation of the eld magnet as described above. By rotating the ileldmagnet, the armature |36 is rotated either in a clockwise or acounter-clockwise motion as seen in Figs. '7 and 8 and the threaded rod|24 is either moved down or up axially. The effect of this rotation andaxial movement of the rod is to move the wire |28 correspondingly in andout of the capillary tube H5.

At the same time, the level oi' the mercury column in the capillary tubefor any given temperature may be lowered by expelling excess mercuryfrom the capillary tube through port |44 in cup |2E. The level of themercury column may be raised by adding mercury from the supply of excessmercury lying in the bottom of compartment L. In the operation of thisinvention, the level of the mercury column is lowered by heating themercury in the reservoir to drive the top of the column up into the cupld to a point where an excess of the mercury will escape through portbill into the compartment L. When the control is held in a verticalposition, this excess supply oi mercury will recede in the capillarytube |5 to a point which is dependent upon the amount of mercuryexpressed from the cup |20 which, in turn, is dependent upon thetemperature to which the mercury is raised. The level of the mercury, inthe capillary tube H5, in turn, can be raised by heating the reservoirifi and the column of mercury to drive the level of the column ofmercury into the cup 42! to a point above the bottom of the cup wherethe walls widen out. rihe control il@ may then be held in a horizontalposition with the port led facing downward and the excess supply of merucury flowing up around the base of the cup |23 will enter the port idd.Upon turning regulating device lili through a semi-circle, a substantialamount of the excess mercury will be trapped in the cup l2@ and come incontact and merge with the top of the column o mercury in the tube l5.The amount of mercury available for the column in tube H5 will thus beincreased. Upon decreasing the temperature oi the mercury column thistrapped mercury will move into the column and thus raise the level ofthe mercury column in tube i l5. The column oi mercury may be furtherincreased by additional mercury from the excess supply incorporated intothe column by a repetition of the above described procedure atprogressively lower temperatures. Thus, it is possible both to increaseand decrease the amount oi mercury in the capillary tube and to raiseand lower the level of the mercury column.

With the two adjustments of the point of oir cuit closing thusobtainable, it is possible to establish a predetermined temperature forclosing the electrical circuit from a wide variety oi temperaturechanges. Furthermore, because oi the accuracy of the thermal control ofthis invention and the minute adjustments in relative position betweenthe thermal electrical contacts, it is possible to predetermine thetemperature point of electrical contact to within a small fraction of adegree of temperature. Another advantage of this invention is found inthe electrical contact that is made with the rotating screw threadedrods 24 or |24. These rods are in continuous electrical Contact with thewires 33 or |33 respectively without interference of their ability torotate in the block 25 or bolt |22, respectively and adjust the positionof the wires 26 or |26 respectively. As a result of this ad vantage, itis possible to adjust the position of the wires 2B or |25 by rotation ofthe screw threaded rods 24 or |24 without disturbance of the electricalcontact between the wires 33 or |33 and 26 or |26 respectively.

Among other advantages, this invention provides a mercury controlleddevice in which the amount of mercury in the contacting column can beeasily varied. Another advantage of this invention is the continuouselectrical contact made with a longitudinally adjustable contact elementwithout hindering the adjustment of the Contact element. rlihe mercuryin the capillary column of this invention is raised and lowered byadding to or taking from the reservoir in the lower compartment. It isan advantage of this invention that in adding mercury to the column inthe capillary tube that the cup lip is in contact with the inner wall ofthe compartment throughout its periphery. This contact is made possibleby the use of the escape port in the side of the cup. The contactbetween the lip and the wall is advantageous in providing a large areawhich can receive the mercury from the reservoir through the escapeport.

Another advantage of this invention is seen in the form shown in Figs.5, 6, '7 and 8. This advantage is the forming of the inner tube as onecontinuous envelope, subdivided merely by a waist portion at which theinner tube walls converge toward each other but do not contact. The sealthat is obtained at this waist portion is also advantageous in itssimplicity of manufacture. The waist portion with its bolt head seal isa strong structure. The electrical contact obtained by the pool ofmercury contained in the upper compartment above the waist supplies ahighly conductive contact between the conducting wire and the threadedrod with the greatest mobility as the mercury which completes thecontact is fluid.

It will be apparent to those skilled in the art f that variousmodifications can be made upon the embodiment of th-e invention shownand described herein Without parting from the principles of theinvention as set forth and for that reason it is notl intended that itshould be limited other than by the scope of the appended claims.

I claim:

l. A thermal control for closing an electrical circuit comprising a.tube, a separating section of said tube, an upper compartment in saidtube above said separating section, a lower compartment in said tubebelow said separating section, a central passage through said separatingsection, a shoulder on the inner surface of said tube wall at each endof said passage, a member extending axially through said passage, a headon one end of said member bearing against one of said shoul ders toprovide a mercury tight nt, a iirst body oi mercury in said lower'compartment forming one oi said separate bodies of mercury, a secondbody of mercury in said upper compartment forming i the other of saidseparate bodies or mercury and positioned adjacent to said passage andseparate from said lower compartment by said mercury tight t, a lead-inwire electrically contacting said second mercury body and an axiallymoving contact wire extending through said member from said uppercompartment to said lower compartment to connect electrically saidlead-in wire to said first body or" mercury through said second body ofmercury.

2. In a tube having an electrical contact as claimed in claim l, aspring bearing against the other of said shoulders on the inner surfaceof said tube, said spring encircling said member and a nut threaded onsaid member bearing against said spring and said other shoulder.

3. A thermal control for closing an electrical circuit comprising atube, a separating section of said tube, a rst compartment in said tubeon one side of said separating section, a second compartment in saidtube at the other side of said separating section, a central passagethrough said separating section, a surface at an angle to the axis ofthe tube at each end of said central passage, a member extending axiallythrough said passage, a portion of said member abutting against theinner surface oi' said tube to provide a mercury tight fit of saidmember in said tube, a iirst body of mercury in the first compartment ofsaid tube, a second body of mercury in the second compartment of saidtube and separated from said first compartment and said first pool or"mercury by said mercury-tight iit, a lead-in wire passing through thetube wall electrically contacting said second mercury body and anaxially moving contact wire extending through said member from saidsecond compartment to said first compartment to connect electricaliysaid leaddn wire to said iirst body of mercury through said second bodyof mercury.

4. A thermal control for closing an electrical circuit comprising atube, a separating section in said tube, an upper coi/npartment in saidtube above said separating section, a lower compartment in said tubebelow said separating section, a

surface at an angle to the axis ol the vtube at each end of said centralpassage, a member extending axially through said passage, a portion ofsaid member abutting against the inner surface of said tube to provide amercury tight nt, a rst body of mercury in said lower compartment, asecond body of .mercury in said upper compartment positioned adjacent tosaid passage and separate from said lower compartment by said mercurytight iit, a lead-in wire passing through the tube wall electricallycontacting said second mercury body, and an axially moving contact wireextending through said member from said upper compartment to said lowercompartment to connect electrically said leadin wire to said first bodyof mercury through said second body of mercury.

References Cited in the file of this patent UNTED STATES PATENTS NumberName Date 291,867 Blainires Jan. 15, 1884 1,955,881 Harper Apr. 24, 19342,438,004 Garbuny et al Mar. 16, 1948 2,498,212 Laverell et al Feb. 2l,1950

